package org.apache.solr.search.function;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Searcher;

import java.util.Map;
import java.util.Arrays;
import java.io.IOException;

/**
 *
 *
 **/
// a simple function of multiple sources
public abstract class MultiFloatFunction extends ValueSource {
	protected final ValueSource[] sources;

	public MultiFloatFunction(ValueSource[] sources) {
		this.sources = sources;
	}

	abstract protected String name();

	abstract protected float func(int doc, DocValues[] valsArr);

	@Override
	public String description() {
		StringBuilder sb = new StringBuilder();
		sb.append(name()).append('(');
		boolean firstTime = true;
		for (ValueSource source : sources) {
			if (firstTime) {
				firstTime = false;
			} else {
				sb.append(',');
			}
			sb.append(source);
		}
		sb.append(')');
		return sb.toString();
	}

	@Override
	public DocValues getValues(Map context, IndexReader reader)
			throws IOException {
		final DocValues[] valsArr = new DocValues[sources.length];
		for (int i = 0; i < sources.length; i++) {
			valsArr[i] = sources[i].getValues(context, reader);
		}

		return new DocValues() {
			@Override
			public float floatVal(int doc) {
				return func(doc, valsArr);
			}

			@Override
			public int intVal(int doc) {
				return (int) floatVal(doc);
			}

			@Override
			public long longVal(int doc) {
				return (long) floatVal(doc);
			}

			@Override
			public double doubleVal(int doc) {
				return (double) floatVal(doc);
			}

			@Override
			public String strVal(int doc) {
				return Float.toString(floatVal(doc));
			}

			@Override
			public String toString(int doc) {
				StringBuilder sb = new StringBuilder();
				sb.append(name()).append('(');
				boolean firstTime = true;
				for (DocValues vals : valsArr) {
					if (firstTime) {
						firstTime = false;
					} else {
						sb.append(',');
					}
					sb.append(vals.toString(doc));
				}
				sb.append(')');
				return sb.toString();
			}
		};
	}

	@Override
	public void createWeight(Map context, Searcher searcher) throws IOException {
		for (ValueSource source : sources)
			source.createWeight(context, searcher);
	}

	@Override
	public int hashCode() {
		return Arrays.hashCode(sources) + name().hashCode();
	}

	@Override
	public boolean equals(Object o) {
		if (this.getClass() != o.getClass())
			return false;
		MultiFloatFunction other = (MultiFloatFunction) o;
		return this.name().equals(other.name())
				&& Arrays.equals(this.sources, other.sources);
	}
}
